Eurorad (France)

The clinical introduction of the hybrid tracer indocyanine green (ICG)-99mTc-nanocolloid, composed of a radioactive and a near-infrared (NIR) fluorescence component, has created the need for surgical (imaging) modalities that allow for simultaneous detection of both signals. This study describes the first-in-human use of a prototype opto-nuclear probe during sentinel node (SN) biopsy using ICG-99mTc-nanocolloid. To allow for fluorescence tracing, a derivative of the conventional gamma probe technology was generated in which two optical fibers were integrated to allow for excitation (785 nm) and emission signal collection (> 810 nm). The ability of this opto-nuclear probe to detect the fluorescence signal of the hybrid tracer ICG-99mTc-nanocolloid was firstly determined ex vivo in (non)SNs samples obtained from 41 patients who underwent hybrid tracer-based SN biopsy in the head and neck or urogenital area. In an in vivo proof-of-concept study in nine of these 41 patients, SNs were localized using combined gamma and fluorescence tracing with the opto-nuclear probe. Fluorescence tracing was performed in a similar manner as gamma tracing and under ambient light conditions. Ex vivo, the gamma tracing option of the opto-nuclear probe correctly identified the SN in all 150 evaluated (non)SN samples. Ex vivo fluorescence tracing in the low-sensitivity mode correctly identified 71.7 % of the samples. This increased to 98.9 % when fluorescence tracing was performed in the high-sensitivity mode. In vivo fluorescence tracing (high-sensitivity mode) accurately identified the SNs in all nine patients (20 SNs evaluated; 100 %). This study demonstrates the first-in-human evaluation of a hybrid modality capable of detecting both gamma and fluorescence signals during a surgical procedure. Fluorescence tracing could be performed in ambient light.

The exposure of CdTe:Cl and Cd0.9Zn0.1Te detectors to increasing doses of ionizing radiation seriously affects their spectroscopic performance. We have investigated the recovery process of the detectors by means of photon (241Am and 57Co) spectroscopy and PICTS (photo-induced current transient spectroscopy) analyses, by studying the evolution with time of their spectroscopic performance and correlating it with the presence of defective states in the material. In our recovery processes, the temperatures of the annealing stages varied from room temperature to 380 K, while the time scale varied from 1 hour to 4 years. We have observed a clear improvement of the material detecting properties with time at room temperature only after long times (years) and for detectors that had not been severely degraded by the irradiation. Thermal treatments were necessary to recover heavier damage. The recovery effect can be associated to the decrease in concentration of some specific defective states, thus assessing the crucial role they play in controlling the charge collection

The homogeneity of the semi-insulating CdTe/CZT crystals will determine the capacity of these semiconductors to be used in pixelized imaging applications using gamma- and X-rays. It appears that the smaller the pixel unit size, the better the material uniformity has to be. Fast characterization methods become therefore, imperative to keep the production costs in industry acceptable. The goal of the present study is to evaluate two experimental methods in their ability to fulfill in a quick and routine manner the material properties: RESISTIVITY MAPPING: a contactless time dependent charge measurement (TDCM) method was used for mapping large scale wafers with spatial resolution of 1.0 mm/sup 2/ in an automatic set-up. It gives very good reproductibility for resistivities higher than 10/sup 6/ Ohm cm and displays full scale image of the resistivity distribution. - INFRARED TRANSMISSION MAPPING: allows the analysis of Te inclusions and an adapted software gives directly the distribution of the precipitate sizes. Samples of THM grown CdTe crystals have been investigated as grown and after various thermal treatments and the pixelized detectors produced from these wafers were tested using a /sup 57/Co radiation source.